The invention relates to a hydrodynamic clutch which can be inserted between a main engine and a drive engine and in particular a component group with a drive engine of a vehicle, an air compressor which can be powered by the drive engine and a hydrodynamic clutch designed to be in the drive connection between the drive engine and the air compressor.
Hydrodynamic clutches are known in a multitude of embodiments for differing purposes. A possible field of deployment for such hydrodynamic clutches is the transmission of torque, and/or general drive capacity from a drive engine of a vehicle to an air compressor, whereby the latter supplies the compressed air plant of the vehicle with compressed air. The advantage of the layout/design of a hydrodynamic clutch in such a power transmission is a cushioning of oscillation between the drive engine and/or a transmission which is connected in series to the drive engine and the air compressor which, as is generally known, is a consequence of the natural property of a hydrodynamic clutch. In this way, for example, it is avoided that in the actuation of a lifting piston in the area of the upper dead point of the piston a negative torque is transmitted back from the compressor onto the transmission which can lead to teeth-chattering and to excessive wear-and-tear in the transmission.
The patent application DE 32 33 567 A1 refers to an exemplary embodiment of a hydrodynamic clutch between a drive engine, here a diesel engine, and an air compressor, here a radial air compressor.
In many embodiments hydrodynamic clutches feature a clutch case which is partially designed with the pump wheel in such a way that the case during the operation of the hydrodynamic clutch rotates with the rotational speed of the input shaft. Thereby the pump wheel encloses, as a rule, together with a case part connected onto to it, the turbine wheel. Thereby the pump wheel and the turbine wheel are placed opposite one another in such a way that they form a mutual work chamber which can be filled with a work medium, for example oil, water or a mixture with one or both of these materials so that a torque, or for example general rotational power is transmitted from the pump wheel via the work medium onto the turbine wheel.
On account of the fact that the case of such a hydrodynamic clutch rotates the connection of a conduit to extract the work medium, through which the work medium can be “cleanly” extracted from the work chamber, is elaborate since appropriate rotating connections are required. Hence, as a rule and in practice, such clutches are laid out in such a way that the case features one or several vent openings out of which the work medium, which is discharged from the work chamber, sprays out. This work medium is collected, for example, as it sprays out, in a collection bath underneath the clutch casing and is led out of the collection bath via appropriate openings or piping.
In order to prevent a braking effect being exerted upon the hydrodynamic clutch, which leads to a deterioration in the degree of efficiency of the drive system, the collection bath is designed in such a way that in principle no oil sump and/or in general no accumulation of work medium can develop which could come into contact with the clutch case. This can be achieved either by the collection bath being designed to be at a sufficient distance from the clutch case or by appropriate drainage possibilities being created in the collection bath which would avoid any accumulation of work medium in it.
Furthermore it is known that in hydrodynamic clutches, on account of the slippage between the pump wheel and the turbine wheel, the work medium gets heated up during operation because of liquid friction. The major part of this heat is dissipated via the work medium flow rate. The flow rate of work medium is however dependent upon the pressure in the feed-line. When the revolution speed of the pump is low, and thereby also that of the turbine wheel, then only low feed-in pressure is available. Simultaneously there is great slippage between the pump wheel and the turbine wheel and a correspondingly great amount of heat output.
This unfavorable combination of low throughput by the hydrodynamic clutch together with simultaneously high liquid friction in the work chamber can lead to an impermissible increase in temperature in the hydrodynamic clutch.
In particular during the deployment of a hydrodynamic clutch in the drive connection between a drive engine, in particular a vehicle drive engine, and an air compressor there also arises the problem that, with an emptied or extensively emptied hydrodynamic clutch this will, via the compressor system, encourage a tendency to oscillation which is undesirable since it produces vibrations and noises.